A variety of arrangements have been proposed in the prior art for adjusting the orientation of a fiber optic lighting fixture after the fixture has been mounted in place. The arrangements typically involve either a gimbaled sphere that can be locked in place onto either a mounting frame or another gimbal, or a spherical eyeball that is captured between a flange and a retention means, which requires an adjusting tool to adjust the eyeball after the eyeball is captured. Such fixtures might possibly allow for minimally sufficient friction force in the fixture to overcome the weight and leveraging of a large diameter, monofilament fiber optic cable. However, these alternatives make access to the eyeball for adjustment of the light after the fixture has been mounted in place nearly impossible or very difficult without access to behind a mounting frame or some sort of unique adjustment tool. Necessitating the use of a unique adjustment tool not only complicates the fixture by requiring a separate, non-readily available tool to adjust the fixture after final adjustments, but it also does not facilitate adjustment of the fixture at-will unless the adjustment tool is available.
A problem that exists with currently available eyeball fixtures is the inability to capture the eyeball between a retention means that is strong enough to firmly lock the eyeball in place (1) without rotating the eyeball within the socket during capture, (2) without damaging the finish on the eyeball, or (3) without deforming the eyeball.
Another problem that exists with currently available fixtures is the inability to easily adjust the fixture, in a reliable or accurate manner, at some future time after firmly positioning the fixture after final adjustments. This difficulty is exacerbated with fiber optic fixtures, since the forces within the fiber tend to move the fixture out of adjustment over time as the fiber curves away from the fixture or the fixture moves out of adjustment during capture of the eyeball within a retention means. This is especially true for large diameter glass-core fiber, and large diameter, solid-core plastic fibers, which can be particularly rigid. Some of the currently available fixtures attempt to solve this problem by the inclusion of a strain relief above the fixture. However, inclusion of a strain relief tends to increase the total fixture height and precludes the use of such fixtures in low-clearance areas.
Another problem that may attribute to the inability to easily adjust a fixture, such as an eyeball fixture, after installation is the amount of pressure that a retaining means places on the eyeball in order to retain the eyeball firmly in place with respect to a retention means. This pressure presents two issues.
First, this pressure needs to be countered by a force applied by the user in order to adjust the eyeball after installation. One possible solution to this problem is the use of an adjustment tool that can lock into place on an output area of the eyeball. However, as stated previously, this solution complicates use of the fixture. In addition, this solution does not create an aesthetically pleasing eyeball surrounding the eyeball's output area because of the need for the eyeball to receive such an adjustment tool either, for example, by housing threads or sockets on the output area surrounding the eyeball.
Second, this pressure may create a large amount of friction between the eyeball and a circular opening, during adjustment of the eyeball position, which would result in more dragging and deformation of the eyeball. One possible solution to this is insertion of a ring, interposed between a retaining means and the eyeball that is made of a lubricious material. However, such material is susceptible to creep or “cold flow” over time, especially when under pressure. Additionally, because such material has innately low frictional forces, an installer would need to exert a greater amount of force on the retention means in order to properly lock the eyeball into place. This not only makes it more difficult for the installer to lock the fixture, but the greater compression force applied on the plastic ring speeds up the cold flow of the plastic. Furthermore, this solution complicates use and manufacture of the fixture.
A significant problem that exists with currently available fixtures that use fiber optics is creation of torque within the fiber due to adjustment of the fixture. If the optics and fiber mounting are part of the fixture itself or if the fiber is securely attached within the fixture itself, then as the aim of the installed fixture is rotated and/or adjusted from below, large amounts of torque can build up within the fiber that can cause the fiber to lose light or fail. This build-up of torque may also contribute to the earlier described problem of moving the fixture out of adjustment over time or during capture of the eyeball within a retention means. Additionally, built-up torque in the system might move the entire fixture out of alignment or possibly push the fixture outwards and away from a ceiling upon which the fixture is mounted, creating a gap between the fixture's mounting frame and the ceiling.
Furthermore, currently available adjustable fixtures do not look aesthetically similar to the down light, wall wash, or accent fixtures with which the adjustable fixtures are designed to compete. Some adjustable fixtures involve a gooseneck or an eyeball that does not have a smooth, aesthetic, simple surface at the output end.
It would, therefore, be desirable to provide an adjustable-aim light pipe fixture that avoids some or all of the foregoing problems.